In my Prax payment is made in services, barter, herd beasts and trade goods, though there is hard cash in Pavis. Cattle in Sartar is how wealth is measured.
It's why the Wicked Writher rites are so important, in my game at least. The khan uses it to bring fertility to the area and for the clan for the next year.
No I am talking about the Orlanthi greeting rituals when one bunch of Orlanthi come across another. Proving that strangers are not dangerous when they arrive at your stead.
EDIT: I can't remember where I read about them. There's a mention in the Sartar book under hospitality for example.
Also by gaining thumbs you are emulating humans, whom you are already superior too. "Thumbs? I have herdmen for that."
Only Morokanth that live with humans need thumbs, or heroes that own an iron sword etc. That's when you heroquest and steal some.
Because i think having them thumbless makes them stand out.
Now they are the "Morokanth who have no thumbs except all of them that have spirit thumbs."
It's a neat idea, but in my view it fixes something that doesnt need fixing that's all.